Refrigerant condenser with key connector



Aug. 18, 1970 R. SMITH ETAL.

REFRIGERANT CONDENSER WITH KEY CONNECTOR 2 Sheets-Sheet 1 Filed 001:. 28, 1968 S m T N E V m Ca flwmum/ ATTORNEY Aug. 18, 1970 RpSMlTH ETAL 1 3,524,329

REFRIGERANT CONDENSER WITH KEY CONNECTOR Filed Oct. 28, 1968 2 Sheets-Sheet 2 ATTORNEY United States Patent 3,524,329 REFRIGERANT CONDENSER WITH KEY CONNECTOR Robert Smith and Edward B. Caden, Dayton, Ohio, as-

signors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Oct. 28, 1968, Ser. No. 770,990 Int. Cl. F25d 19/00 US. Cl. 62-295 4 Claims ABSTRACT OF THE DISCLOSURE In preferred form, a refrigerant compressor and condenser support system for use in a domestic refrigerator including a pad supporting a compressor unit. An aircooled refrigerant condenser of the tube and sheet type is wound on itself and is fixedly secured to the pad 'by means including an elongated multi-toothed key member directed through segments of the wound condenser sheet. The key engages refrigerant tube passes on the wound condenser sheet segments to maintain a desired air flow spac'mg between wound segments of the sheet while reducing vibration noises in a domestic refrigerator machinery compartment.

This invention relates to refrigerating apparatus having compressors operated at high revolutions per minute and more particularly to an improved suspension system for supporting an hermetically sealed refrigerant compressor, cooling fan and condenser component on a single support pad adapted to be connected within the machinery compartment of a domestic refrigerator and removable therefrom for repair.

Domestic refrigerator apparatus often includes an hermetically sealed compressor and drive motor operated at a high rate of rotation to produce a maximum refrigerating capacity for a given compressor piston displacement.

Such units are characterized by having a relatively compact dimensional configuration and are generally located in a lower machinery compartment of a domestic refrigerator in close association with refrigerant condenser components and the like. One problem with systems of this type is that the hermetically sealed motor compressor unit often produces high frequency vibrations in supporting structures of the unit. Furthermore, refrigerant discharged from the compressor can produce pulsing noises in a closed refrigerant circuit. Where the refrigerator is used in a domestic household such noises are objectional.

In certain cases, it is found desirable to mount the hermetically sealed motor compressor unit and a refrigerant cooling condenser adjacent one another whereby a single fan can direct a forced draft of air across the condenser and hermetically sealed compressor for cooling them during the operation of the domestic refrigerator.

In order to improve the serviceability of such a plurality of operating components, it is further desirable to secure each of the components to a single support pad that is readily inserted into and removed from a lower refrigerator machinery compartment.

Such an arrangement of refrigerating components increases the noise problems mentioned above and require a substantial number of separate sound dampening components and connectors to maintain a low level of noise during refrigeration apparatus operation. This is especially the case when the condenser unit is of the sheet tube type wherein the sheet heat transfer component of the condenser is wound on itself to form a compact refrigerant cooling package occupying a limited extent of the working machinery compartment of the refrigerator.

It is found that where the hermetically sealed motor compressor unit is supported on the same pad assembly as the condenser that noise level during operation is reduced where the tube and sheet type of condenser is securely fastened to the pad assembly. In the past, this has been attained by the provision of a plurality of separate connector elements interposed between horizontal segments of a wide, thin heat transfer sheet in the condenser. In this case, the connector elements include segments thereon interleaved with the sheet of the condenser and fixedly secured thereto. Typically, plural connector elements are required at each end of the wound tube and sheet condenser unit to reinforce the condenser so that it can be fixedly secured to the pad assembly to produce a degree of structural integritybetween the condenser and the supporting pad assembly that is sufiicient to produce a reduction in noise during refrigerator operation.

While existing systems are suitable for their intended purpose, they require the placement and securing of a substantial number of separate parts that results in a substantially increased cost of manufacture. Further, the connectors often collect lint, dust and the like which can block cooling air flow across the condenser.

Accordingly an object of the present inventionis to reduce noise levels in a domestic refrigerator where the refrigerator has a wound sheet tube type refrigerant condenser in its machinery compartment and to do so by firmly securing the condenser to its support frame or pad by a single connector element which can be quickly as-. sembled at low cost and which is self-cleaning during refrigerator operation to prevent an accumulation of lint or dust in air flow passageways through the condenser.

One working embodiment of the invention which accomplishes the above object is in a domestic refrigerator having a refrigerant compressor and condenser unit on a single support pad adapted to be connected between the side frame members of a bottom machinery compartment of a refrigerator. The embodiment includes a key configured element that is removably seated in -place through a plurality of loop segments in a wound sheet member of the condenser to relatively rigidly, fixedly interconnect adjacent ones of a plurality of refrigerant tube passes on the wound segments of the sheet to one another and to the support pad to define a fixed connection of the condenser to the pad for reducing vibrations therebetween.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

FIG. 1 is a view in side elevation of a domestic refrigerator having the base thereof partially sectioned to show a machinery compartment including the combination compressor and condenser support system of the present invention;

FIG. 2 is a view in perspective showing a removable support pad and refrigeration components constituting the main operative parts of a domestic refrigerator incorporating the present irrventionj FIG. 3 is an enlarged fragmentary view in top elevation showing the relationship of a key connector in its interlocked, seated relationship with tube or conduit passes in the condenser unit of the improved system;

FIG. 4 is an enlarged, end elevational view of the improved refrigerant condenser arrangement of the present invention;

FIG. 5 is a fragmentary view in vertical section taken along the line 55 of FIG. 4, looking in the direction of the arrows;

FIG. 6 is a fragmentary, top, elevational view showing the relationship between the key connector of the present invention and the condenser when the connector is unlocked.

FIG. 7 is a view like FIG. 6 with the key connector perpendicular to the tubes on the condenser.

FIG. 8 is a side elevational view of the condenser and pad assembly showing the key connector in place therein;

FIG. 9 is a top elevational view of the key connector of the invention; and

FIG. 10 is a front elevational view of the key when it is in its seated relationship with respect to the assembled condenser unit.

Referring now to the drawings, in FIG. 1, a domestic refrigerator 10 is illustrated having an outer shell 12 surrounding an inner liner 14 in spaced relationship thereto. The outer shell 12 and inner liner 14 define a space 15 which is filled with suitable thermal insulating material 16, such as formed in situ foamed polyurethane material.

In the illustrated arrangement, a base of the shell 12 includes a front kick-panel thereon which defines a raised segment in the base 20 below which is located a machinery compartment or space 24. In the illustrated arrangement, which is merely representative of a domestic refrigerator arrangement suitable for association with the present invention, the side walls of the outer cabinet 12 are illustrated to have integrally formed depending pads or support feet 26 and an integrally formed rail 28 serving as a reinforcing framework around the base of the refrigerator outer shell 12.

A stamped sheet metal support pad 30 is directed through the machinery compartment 24 from rail 28 at one side of shell 12 to the rail 28 on the opposite side of the outer shell 12. It includes upwardly turned ends 32, 34 thereon. A pair of spaced apart channels 35, 36 reinforce the length of the pad 30. At the turned up ends 32, 34 the channels 35, 36 have openings 37 therethrough to receive screws 39 that fixedly secure these ends to the side rail 28.

Thus, the pad 30 is relatively fixedly secured to the outer shell 12.

In accordance with certain principles of the present invention, the single pad 30 supports an hermetically sealed motor compressor unit 38 on one end thereof and a sheet and tube type refrigerant condenser 40 on the opposite end thereof. Intermediate the compressor unit 38 and the condenser 40 is located an air cooling fan unit 42. The hermetically sealed, motor compressor unit 38, condenser 40 and fan assembly 42 are supported by the pad 30 to be handled as a unit that can be readily inserted through a rear access opening 44 in the rear wall of the outer cabinet 12 into the machinery compartment 24. The access opening 44 is closed by a baffle plate 46 that is readily removed when it is desired to service any one or more of the components on the pad.

Units of the above-described type are desirable in that it definitely improves ease of service, and, furthermore, enables a substantial number of component parts in the refrigeration system to be handled as one unit during manufacture and assembly thereof.

In the illustrated arrangement, the basic refrigeration system includes a discharge line 48 from the hermetically sealed motor compressor unit 38 that connects to one end of a continuously formed condenser tube 50 that is wound sinusoidally along the length of a heat transfer sheet 52 of the condenser 40.

The tube 50 includes a plurality of parallel passes seated in longitudinal grooves 53 in the sheet member 52. The member 52 is fixedly secuerd to the passes of tube 50 by suitable means such as spot welds. An outlet 54 from condenser 40 is directed through the machinery compartment and upwardly through the base 20 of the refrigerator cabinet to be connected to a suitable refrigerant expansion means (not shown) such as an elongated capillary tube to the inlet of a refrigerant evaporator unit 56 that is connected by a suction line 58 to the inlet of the compressor in the unit 38.

In the illustrated arrangement, the hermetically sealed, motor compresor unit 38 is of the high side type including an external superheat exchanger 60 that includes an inlet connected directly to the discharge line of the compressor and an outlet that is directed through a mufller 62, thence into the interior of the hermetically sealed compressor unit 38. The cooling action of the interchanger 60 serves to reduce the temperature of the refrigerant gas so that it will, upon returning to the shell interior, cool the operating electric motor therein prior to passage thereof through the discharge line 48 and to the condenser 40.

When the motor compressor unit 38 is operated during a refrigeration cycle of operation, it discharges hot gas from its compressor through the superheat coil 60 and the mufiier 62, thence through the discharge conduit 48 and the continuously formed, sinusoidally wound conduit 50 on the sheet member 52 of condenser 40. Hot gas flow to the condenser 40 is cooled and liquefied and discharged through the outlet 54 across the capillary tube into the inlet of the evaporator 56. Expansion of the liquid refrigerant passing through the evaporator 56 will remove heat from a refrigerator food storage compartment 64 which, in one working embodiment, is divided into a side-by-side below freezing compartment and an above freezing compartment, both of which have access openings thereto closed by vertically hinged doors 66.

In the illustrated arrangement, the motor for driving the compressor in the unit 38, in one working embodiment, has a /3 horsepower rating and an operating speed, when energized, of 3,550 revolutions per minute. To prevent direct transfer of vibrations in the unit 38 to the pad 30, the unit includes resilient pads 68 on either end thereof.

Furthermore, the illustrated system includes a rotary compressor connected to the high speed drive motor that produces a discharge pulse through the line 48 on each revolution of the motor. These pulsations are, to a degree, nullified by the mufiler 62 but, in order to further reduce these vibration noises in the system, in accordance with the invention, improved means are provided to fixedly secure the condenser 40 in place on the pad 30 formovement therewith. This system has been found to noticeably reduce the noise level of operation of systems of this type and will be more specifically described in following material.

The fan assembly 42 interposed between the noise producing motor-compressor unit 38 and the closely adjacent located condenser 40, more particularly, includes a sheet metal housing 70 having its base fixedly connected to the pad 30 and a fan opening 72 coaxially aligned with the condenser 40 between it and the hermetically sealed motor compressor unit 38. A fan motor 74 is secured on one side of the housing 42 and it includes a shaft which has a fan impeller 76 secured thereto and rotated within the fan opening 72.

During refrigeration operation, to improve heat removal from the condenser 40, the fan impeller 76 is rotated by the motor 74 at a substantially high rpm. in the order of 1250 to draw air from the right side of the condenser 40 as viewed in FIG. 2 to the left side thereof, thence to be discharged across the unit 38. In or der to maintain effective air cooling of the condenser 40, it is important that it have a predetermined configuration to define a substantial, cross sectional, planar extent for air flow produced by the operation of the fan impeller 76. Accordingly, in the illustrated arrangement, the sheet member 52 includes an inwardly located end 78 about which the sheet element 52 is wound to define a plurality of looped segments around the end 78, terminating in a sheet end segment 80 opposite to the end 78 at a point immediately above the pad 30.

In the illustrated embodiment of the invention, the sheet member 52 runs from the end 80 to define a base 82 carried on flat upper surface portions of the pad assembly 30 as is best illustrated in FIG. 4.

Each of the looped segments includes a generally trapezoidally shaped end elevational view and they are of progressively reduced perimetrical length from the outside end 80 to the inwardly located end 78 through the total winding of the member 52.

Furthermore, each of the looped segments includes an upper and lower horizontal extent that is separated from an adjacent upper and lower horizontal extent of a contained loop progressing from the outside of the unit to the inside thereof. Between each of the loops is formed a plurality of air flow passageways 84 extending from the inlet end 86 of the condenser to the outlet end 88 thereof. Each of the passageways 84 is in communication with one another to form a spiral-like path through the full extent of the winding of the sheet member 52 from the inner end 78 to the outer end 80 thereof and all of the openings 84 define a cross-sectional, flow area in coaxial alignment with the fan opening 72 whereby, during rotation of the impeller 76, air will be drawn through the openings 84 without obstruction and across the conduit 50 wound on the sheet element 52 in good convective heat transfer relationship therewith.

In accordance with certain principles of the present invention, in order to reduce noise level in the combination condenser and compressor support system and to assure an unobstructed air flow across the tube 50, a single, elongated, key connector element 90 is disposed with respect to the condenser 40 and support pad 30 so as to interlock each of the looped segments of the condenser 40 with respect to one another so as to maintain a desired vertical spacing of the air flow passageways 84 and, furthermore, to hold each of the horizontally disposed segments of the wound sheet member 52 against relative movement with respect to each other because of the air flow. Additionally, the single key connector element 90 is included to interlock the joined segments of the condenser 40 securely to the pad assembly 30 thereby to prevent vibratory movement between the conden ser 40 and pad 30 so as to maintain a desired operating noise level in the completely integrated system.

More particularly, and as is best illustrated in FIGS. 9 and 10, the connector element 90 includes an upper handle portion 92 and a tapered, depending nose portion 94. Intermediate the handle 92 and nose portion 94 is a central enlarged body segment 96 which, as is best seen in FIG. 5, fits between the horizontal segments of the wound sheet member 52 above the inner end 78 to reinforce the core of the wound element 52.

The opposite edges 98, 100 of the key element 90 each include a plurality of outwardly directed teeth 102, together forming an edge recess or tube seat 104 between which is located a thin section waist segment 106 of the element 90.

In accordance with certain principles of the present invention, the horizontal segments of the wound sheet member 52 each includes an opening 108 and the openings 108 are vertically aligned to define a path to insert the key element 90 completely through the condenser 40 from its top to its bottom.

Each of the openings 108 is bridged by first and second segments 110, 112 of the continuously formed tube 50. The opening bridging segments 110, 112 are each seated in one of the recessed seats 104 in the edges 98, 100 of the key element 90 and the thickness or width of the waist segment 106 is substantially equal to the distance between the outer diameter of the adjacent bridging segments 110, 112 when the key is arranged at a slight inclination from being perpendicular to the longitudinal axes of the segments 110, 112.

Furthermore, the teeth 102 along the opposite edges of the key element 90 are interposed between the adjacent horizontal segments of the sheet element 52 and function to maintain a desired vertical separation therebetween, as is best seen in FIG. 5.

As is best seen in FIG. 9, the edges 98, 100 of the key element 90 have a taper or lead angle. Thus, when the key element 90 has a head-on view as in FIG. 10, it is located degrees from a horizontal reference line as seen in FIG. 9. The lead angle enables the key element 90 to be easily located in an interlocked relationship with each of the pairs of bridging segments 110, 112 across the sheet member openings 108.

Thus, when the key element 90 is positioned as shown in FIG. 6 during assembling of the condenser 40 to the pad 30 and rotated to the position shown in FIG. 7 where key element 90 is perpendicular to the bridging elements 110, 112, the teeth 102 will move into an interleaved relationship with the horizontal segments of the sheet member 52 without any undesirable interference therebetween and the waist segments 106 will slightly spread the adjacent ones of the pairs of bridging segments 110, 112, as is seen in FIG. 7.

The bridging segments will spring back to a substantially parallel relationship as is seen in FIG. 3 when the key element 90 is at its angular relationship with respect to the perpendicular of FIG. 7 whereby the bridging segments 110, 112 serve to eflectively spring urge or bias the key element 90 against limit stops or edges 114, 116 formed in a generally S-shaped opening 118 in the pad 30 through which the nose 94 of the key element 90 is inserted prior to rotation of the key connector element into its interlocked position.

The nose segment, as it is rotated within the S-shaped opening 118, has an upper edge 119 thereon in underlying relationship with the pad 30 at the opening 118 therethrough so as to interlockingly connect the key element 90 to the pad against vertical movement with respect thereto. Additionally, the movements of the teeth 102 on each of the edges of the key connector element 90 will further secure each of the horizontal segments of the sheet member 52 vertically with respect to one another as well as with respect to the pad 30 to thereby produce a good, positive interconnection of the condenser unit 40 to the pad 30. The connection has been found to result in a low level of noise in the total assembly and, further, produces a positive maintenance of the air flow passageways 84 through the wound condenser structure from the inlet end 86 to the outlet end 88 thereof.

By virtue of the unique configuration of the key element 90, the interconnection is produced merely by inserting the key element 90 into the vertically aligned openings 108 and thereafter twisting it by grasping the handle 92 and moving the key element slightly more than 90 degrees gpn the position shown in FIG. 6 to that shown in In one working embodiment of the invention, the key was configured in accordance with the following schedule.

CONDENSER KEY CONFIGURATION It is important to note the relative rigidity of the key as compared to that of the tubing and sheet material interlocked therewith. The key in the illustrated embodiment is .135 inch thick and the thin, good heat dissipating sheet member of the condenser is .015 inch thick and held by the key element so that the unit is maintained in a firmly retained relationship with the pad 30 while maintaining the vertical height of the air flow passageways through the condenser.

Another feature of the above-described arrangement is that the key connector element 90 is arranged with its edges 98, in line with the air flow path through passageways 84. This presents a knife-edge profile, best seen in FIG. 5, which offers little or no surface for accumulation of dust, lint or the like to obstruct air flow. The connector element thereby tends to be self-cleaned by cooling air fiow through condenser 40 during refrigerator operation. Accordingly, product reliability is improved.

While the embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is:

1. A compressor and condenser support assembly adapted to be removably located within a bottom machinery compartment of a domestic refrigerator com prising, a bottom pad, an hermetically sealed motor driven compressor unit, means for connecting said compressor unit on one end of said pad, a fan housing supported on said pad in close spaced relationship to said hermetically sealed motor driven compressor unit, a fan within said housing for drawing air therefrom to be discharged against said compressor unit for cooling same, a thin sheet member having a length greater than its width, said sheet having one end edge thereon located above and in spaced relationship to said pad, said sheet member being wound from said one end edge continuously therearound to form a plurality of looped segments, a refrigerant tube on said thin sheet member formed sinusoidally across the width of said member and including an inlet and an outlet adapted to be connected in a refrigerant circuit, said refrigerant tube including a plurality of tube passes extending longitudinally of said sheet member along the length thereof, said loop segments of said wound sheet member defining a plurality of air passageways through said wound sheet member, said plurality of passageways being in coaxial relationship with said fan, said fan operative to draw air through said passageways and across said tube passes for cooling refrigerant flowing therethrough, means defining a plurality of vertically aligned openings through said Wound sheet member, a pair of said plurality of tube passes bridging each of said openings and being spaced apart a predetermined distance, an elongated key connector element extending through the vertically aligned openings of said sheet member from top to bottom of said wound segments, said key connector element having side edges and a plurality of outwardly directed teeth on each edge forming a plurality of tube seats at spaced apart points along the length of said element, said teeth each including inclined surfaces thereon holding each of said pairs of tube passes in engagement with said tube seats thereby to reinforce said looped sheet segments, said teeth being located between said looped sheet segments to hold them apart from each other and thereby maintain said air passageways, and coacting means on said key connector element and pad for removably fixedly securing said element and pad to one another.

2. A refrigerant condenser comprising, a base support member, a sheet member having a length greater than its width, said sheet member having first and second ends thereon and being wound about said first end to form a plurality of looped segments of said sheet material above said support member, a refrigerant tube on said sheet member formed sinusoidally across the width thereof and including a plurality of parallel, longitudinal reaches, a plurality of vertically aligned openings through said sheet member, a plurality of pairs of longitudinal tube reaches bridging said aligned vertical openings, an elongated key member directed through said plurality of vertically aligned openings and including a nose segment on one end thereof interlockingly connected to said bracket, said key member having a handle on the opposite end thereof, a plurality of outwardly directed crests on the opposite edges of said key member defining a plurality of spaced apart waist segments on said key element along the length thereof, each of said waist segments being in engagement with a pair of said tube passes bridging one of said vertical openings, said crests including a segment on the edge of said key located outwardly of the waist segment and serving to maintain segments of said wound sheet member apart from one another to define a plurality of open air passageways through said wound sheet for cooling refrigerant passing through said tube passes, said key member serving to securely fasten all portions of said Wound sheet adjacent to said pairs of waist-engaging tube passes to prevent vibratory movement between said sheet and said bracket.

3. A refrigerant circuit subcombination comprising a support pad adapted to be connected to side frame members of a refrigerator cabinet, an hermetically sealed motor driven compressor connected to one end of said pad, a discharge conduit from said compressor, a fan housing connected on one side of said hermetically sealed motor compressor unit including an opening therein, a fan drive motor supported on said housing including a drive shaft, a fan impeller secured to said shaft within said opening for drawing air therethrough across said hermetically sealed motor compressor unit and said drive motor, a refrigerant condenser including a continuously formed sinusoidally shaped refrigerant tube having one end thereof connected to said compressor discharge conduit, said tube having an outlet adapted to be connected to an evaporator of a refrigerant system, a sheet member of heat transfer material secured to said tube, said sheet member having a length greater than its width, said sheet member including opposite ends thereon and being wound about one of said ends to form a plurality of looped segments each including part of the continuously formed tube thereon, said plurality of looped segments having a predetermined spacing therebetween to form an axial opening across the width of said sheet member coaxially aligned with said condenser fan housing to define air transfer passageways in intimate convective heat transfer relationship with said refrigerant tube, a plurality of openings in said sheet member being aligned vertically therethrough and extending through each looped segment of said sheet member, a pair of tube passes bridging each of said vertically aligned openings, a key element located within said opening including a first plurality of teeth on one edge thereof defining a plurality of tube receiving seats at spaced apart points along the length of said key element, first vertically aligned tubes in said plurality of pairs of tube passes located in said seats, a second plurality of teeth directed outwardly of the opposite edge of said key element and defining a second plurality of spaced apart seats along the opposite edge of said key element, second vertically aligned tubes in said plurality of pairs of tubes located in said second seats, said first and second vertically aligned tubes being a predetermined vertical distance apart from one another thereby to hold said looped segments in a predetermined plurality of vertically spaced horizontal planes to positively maintain a predetermined planar extent of heat transfer air flow passageway through the width of said wound sheet member, said support pad including an offset opening therein defining a pair of spaced apart stop edges, said key element including a nose portion having surfaces thereon engageable with said stop edges to locate said first and second plurality of teeth on said key element in a plane slightly to one side of a perpendicular alignment with said pairs of tube passes, said key element including a plurality of spaced apart Waist segments along the length thereof between the tube seats on the opposite edges thereof, said waist segments having a width slightly greater than the distance between the outer diameter of adjacent tubes in each pair of tube passes whereby said waist segments will be in biased engagement with said tube passes when said key element is in its one side of a perpendicular alignment to interlock said tube pass pairs to said key element, coacting means on said nose portion and said support pad for vertically interlocking said pairs of opening bridging tube passes with respect to said support pad and thereby serving to connect said looped segments of said sheet material securely to said support pad to prevent vibratory movements therebetween.

4. A refrigerant condenser comprising, a support pad adapted to be removably connected to side frame members of a refrigerator cabinet, a refrigerant condenser including a continuously formed sinusoidally shaped refrigerant tube having an inlet and an outlet, a sheet member of heat transfer material secured to said tube, said sheet member having a length greater than its width, said sheet member including opposite ends thereon and being wound about one of said ends to form a plurality of looped segments each including part of the continuously formed tube thereon, said plurality of looped segments having a predetermined spacing therebetween to form an axial opening across the width of said sheet member to define air transfer passageways in intimate convective heat transfer relationship with said refrigerant tube, a plurality of openings in said sheet element being aligned vertically therethrough and extending through each looped segment of said sheet member, a pair of tube passes bridging each of said vertically aligned openings, a key element located within said opening including a first plurality of teeth on one edge thereof defining a plurality of tube receiving seats at spaced apart points along the length of said key element, first vertically aligned tubes in said plurality of pairs of tube passes located in said seats, a second plurality of teeth directed outwardly of the opposite edge of said key element and defining a second plurality of spaced apart seats along the opposite edge of said key element, second vertically aligned tubes in said plurality of pairs of tubes located in said second seats, said first and second vertically aligned tubes being a predetermined vertical distance apart from one another thereby to hold said looped segments in a predetermined plurality of vertically spaced horizontal planes to positively maintain a predetermined planar extent of heat transfer air flow passageway through the width of said wound sheet member, said support pad including an offset opening therein defining a pair of spaced apart stop edges, said key element including a nose portion having surfaces thereon engageable with said stop edges to locate said first and second plurality of teeth on said key element in a plane slightly to one side of a perpendicular alignment with said pairs of tube passes, said key element including a plurality of spaced apart Waist segments along the length thereof between the tube seats on the opposite edges thereof, said waist segments having a width slightly greater than the distance between the outer diameter of adjacent tubes in each pair of tube passes whereby said waist segments will be in biased engagement with said tube passes when said key element is in its one side of a perpendicular alignment to interlock said tube pass pairs to said key element, coacting means on said nose portion and said support pad for vertically interlocking said pairs of opening bridging tube passes with respect to said support pad and thereby serving to connect said looped segments of said sheet material securely to said support pad to prevent vibratory movements therebetween.

References Cited UNITED STATES PATENTS 

